1,720,955 research outputs found
Effect of constant-DI pacing on single cell cardiac dynamics
No full textUniversity of Minnesota M.S. thesis. 2020. Major: Biomedical Engineering. Advisor: Alena Talkachova. 1 computer file (PDF); 56 pages.Cardiac alternans, beat-to-beat alternations in action potential duration (APD), is a precursor to fatal arrhythmias such as ventricular fibrillation (VF). Previous research has shown that voltage driven alternans can be suppressed by application of constant diastolic interval (DI) pacing protocol. However, the effect of constant-DI pacing on cardiac cell dynamics and its interaction with the intracellular calcium cycle remains to be determined. Therefore, we aimed to examine the effects of constant-DI pacing on the dynamical behavior of isolated cardiac myocytes along with the influence of voltage-calcium (V-Ca) coupling on these changes. Cardiac cell dynamics were analyzed in a non-linear neighborhood close to the bifurcation point using a hybrid pacing protocol, a combination of periodic and constant-DI pacing. We demonstrated that in a small region beneath the bifurcation point constant-DI pacing caused the cardiac cell to remain alternans-free after switching to the constant-BCL pacing, thus introducing a region of bistability (RB). Strong V-Ca coupling increased the size of the RB. Overall, our findings demonstrate that experimental constant-DI pacing on cardiac cells with strong V-Ca strength may induce permanent changes to cardiac cell dynamics increasing the utility of constant-DI pacing.Parthiban, Preethy. (2020). Effect of constant-DI pacing on single cell cardiac dynamics. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/217118
The immunobiology of cardiac macrophages: multifaceted drivers of dysfunction and resolution across the spectrum of heart failure
Get PDFUniversity of Minnesota Ph.D. dissertation. June 2025. Major: Integrative Biology and Physiology. Advisor: Xavier Revelo. 1 computer file (PDF); xi, 177 pages.Cardiovascular diseases remain the leading cause of death worldwide. Recent studies have revealed critical roles for inflammation in the onset and progression of heart disease, with macrophages emerging as key immune players in this context. Cardiac macrophages - highly plastic cells with diverse phenotypes - originate from two major sources thatinfluence their functions. Cardiac resident macrophages (CRMs) arise from embryonic progenitors and populate the heart during development, while monocyte-derived macrophages (MoMFs) are recruited from the bone marrow in response to injury. MoMFs typically mediate inflammatory responses and contribute to tissue damage, whereas CRMs are generally anti-inflammatory and play protective roles in both homeostasis and disease. However, CRMs are a heterogeneous population comprising multiple subtypes with distinct genetic signatures that influence their function across various disease states.
This thesis investigates how macrophage heterogeneity, arising both from their origin and microenvironment, relates to their functional roles. Using both acute and chronic injury models, I examine the diverse roles of cardiac macrophages in modulating disease outcomes, with a specific focus on their bidirectional influence. In a model of acute pressure overload, I define CRM contributions to both fibrosis and angiogenesis. While overall a protective cell population, I identify a subset of CRMs that can aggravate fibrosis through the release of Chemokine (C-C motif) ligand 24 (CCL24). Finally, I characterize
a specialized subset of cardiac macrophages known as lipid-associated macrophages (LAMs), which exhibit conserved genetic features across tissues and play a role in modulating disease in obesity- and hypertension-associated heart failure.
Together, these studies highlight the functional duality and context-specific behavior of macrophages in cardiac pathology. This thesis underscores the importance of dissecting macrophage heterogeneity to inform targeted therapeutic strategies for heart failure.Parthiban, Preethy. (2025). The immunobiology of cardiac macrophages: multifaceted drivers of dysfunction and resolution across the spectrum of heart failure. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/276806
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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